Miniature devices are flooding the markets. As device size continues to decrease, it has become difficult to find batteries that fit the size and power demands of ever-shrinking electronic devices. Battery systems (e.g., lithium ion batteries (LIB)) as one option for the energy and power supply of portable and autonomous systems do not meet the requirements of miniaturized devices, and often, a battery is many times larger than the device within which one would seek to employ it. Furthermore, bridging the gap between the power densities of capacitors (fast energy release) and the energy densities of batteries (long-lasting energy) remains a fundamental problem in electrochemical energy storage (EES).
In many of devices, such as microelectromechanical systems (MEMS), or implantable medical sensors, the overall size is determined by the dimensions of the battery. Therefore, both design and functionality are dependent upon the battery assembly being employed, and its architecture. In traditional batteries, the anode and cathode materials are often compounded with a conductive additive and polymeric binder and subsequently casted onto current collectors such as metal foils. An inert and porous separator soaked in liquid electrolyte or a solid electrolyte is then sandwiched by the anode and cathode assembly. In this stacked architecture of composite electrodes, the individual layers are typically 10's to 100's of microns in thickness. While this architecture works well for the conventional use in applications such as laptops and cell phones, it is poorly transferrable to small-scale devices.
Thin film batteries, on the other hand, which are often employed in MEMS applications, have only a few micron thick electrode films that are separated by a few micron thick solid electrolyte, such as LiPON, and supported on a substrate. The areal energy density in thin film batteries is correlated to the electrode film thickness. Since the solid electrode materials are often poor ionic conductors, higher energy density typically results in a reduction of power capability.
Thus, a need exists for a new battery assembly that can be employed in microelectronic devices and other devices without unduly compromising or negatively affecting the power capabilities and/or architecture of the device.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicant in no way disclaims these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.